1. Technical Field
The present invention relates to an ink composition for ink jet recording.
2. Related Art
There is known an ink jet recording apparatus performing recording of images and letters by discharging minute droplets of an ink composition from nozzle holes of a recording head and allowing the ink composition to adhere to a recording medium. As the ink composition used in such ink jet recording, for example, an ink composition containing various components such as a coloring material, a surfactant, water, and an organic solvent is known. A substantially water-free oily (nonaqueous) ink composition has also been developed.
In ink jet recording, a variety of performances are required in each of the components such as an ink set, an ink composition, a recording apparatus, and a recording medium, and an advanced balance among these components is also required.
For example, JP-A-2012-012432, JP-A-2012-046671, and JP-A-2010-018730 propose technologies for improving the drying property of an ink composition after recording on a recording medium. JP-A-2012-012432 discloses an ink composition containing a hydrocarbon solvent, a solvent having an ester group and an ether group, and a solvent soluble in both solvents. JP-A-2012-046671 discloses an ink composition including an amide solvent (an ether amide). JP-A-2010-018730 discloses an ink composition including three types of alcohols having different boiling points. These patent documents describe that in the above-mentioned oily ink compositions, the drying properties after printing on recording media are improved.
However, the ink composition in JP-A-2012-012432 contains a hydrocarbon solvent, and the ink composition in JP-A-2010-018730 contains alcohols. Consequently, in these ink compositions, the solubility of the resin blended as a fixing agent may be insufficient. In such a case, even if the drying property can be improved, there are risks of deterioration of physical properties of the ink composition owing to, for example, precipitation of the resin, a difficulty of securing the abrasion resistance of recorded matter, and restriction in selection of the resin for fixing. In the technology disclosed in JP-A-2012-046671, in the case of adding an ether amide to an aqueous ink composition, an improvement in drying property can be expected. However, since the ether amide itself is hygroscopic, in the case of adding an ether amide to a nonaqueous ink composition (oily ink composition), the drying property may rather decrease.
However, even in a case of using a solvent that can improve the drying property, if the drying property is too high, the solvent of the ink droplets adhered onto a recording medium may evaporate before sufficient wet-spreading of the ink. In such a case, the dot size of the ink droplets adhered onto a recording medium is small, and thereby the filling of the image with aggregates of a plurality of ink droplets becomes worse to cause occurrence of linear unevenness in the resulting image, resulting in a reduction in image quality.